1. Field of the Invention
This invention relates to a communication apparatus having a transmission electric power control circuit, a communication apparatus having a control signal generation circuit generating a control signal indicative of compensating a table for determining a transmission power and a communication system in which transmission electric power is controlled.
2. Description of the Prior Art
A communication apparatus having a transmission electric power control circuit is disclosed in Japanese patent application provisional publication No. 6-13956. In such a prior art communication apparatus, a transmission electric power is determined in accordance with an electric power of the received pilot signal. The pilot signal is detected by a mobile unit and used to estimate the power of transmission of the mobile unit. A spread spectrum communication equipment with transmission power control is also disclosed in Japanese patent application provisional publication No. 08032513A. In such a prior art spread spectrum communication equipment, a transmission power of a base station is determined in accordance with a detected control bit from a mobile unit.
There are two types of controlling transmission power in mobile unit communication employing the CDMA system, that is, an open loop control effected by a mobile unit in accordance with the detected electric power of the received signal and a closed loop control effected by feeding back a control signal to a mobile station from a base station.
Tomohiro Doi and Mamoru sawahashi disclosed Power control by employing Interference Power for DS-CDMA in TECHNICAL REPORT OF IEICE. A P94-75, RCS94-99 (1994-10) at p63-68 by THE INSTITUTE OF ELECTRONICS. INFORMATION AND COMMUNICATION ENGINEERS. A transmission power at a mobile unit is controlled such that a signal to Interference-plus-Noise power Ratio (SINR) is maintained at a constant value at a base station through a transmission power control bit (TPC bit) from the base station to the mobile unit to provide a closed loop controlling. The mobile unit increases or decreases the transmission power in accordance with the TPC bit periodically inserted in a data frame.
The aim of the present invention is to provide an improved communication apparatus and an improved communication system.
According to the present invention, a first communication apparatus is provided, which comprises: a receiving and transmitting portion having an antenna for receiving a first CDMA radio wave signal, detecting a desired wave component including a control signal from the first CDMA radio wave signal, and transmitting a second CDMA radio wave signal; a detection portion for detecting an electric power of the detected desired wave component; a table portion for storing a relation between the detected electric power and an electric power of the second CDMA radio wave signal to be transmitted, the control signal indicating compensation of the relation; a demodulating and detection portion for demodulating the detected desired wave component and outputting demodulation data and for detecting the control signal from the detected desired wave component; a compensation portion for compensating the relation in accordance with the detected control signal; a determining portion for determined an actual electric power of the second CDMA radio wave signal to be transmitted in accordance with the compensated relation; and a transmission power control portion for controlling a transmission power of the second CDMA radio wave signal in accordance with the actual electric power.
The first communication apparatus may further comprise: a sampling and storing portion for sampling and storing the detected electric power; and a compensating range determining portion for determining a portion of a range of the detected electric power in accordance with the stored detected electric power, wherein the compensation portion compensates the relation within the range.
In the first communication apparatus, the compensation portion may comprise an allowable range data receiving portion for receiving allowable range data and the compensation portion compensates the relation within the allowable range of the electric power of the second CDMA radio wave signal to be transmitted in accordance with the received allowable range data.
According to the present invention, a second communication is provided, which comprises: a transmitting and receiving portion having an antenna for transmitting a first CDMA radio wave signal including a control signal, receiving a second CDMA radio wave signal, and detecting a desired wave component from the second CDMA radio wave signal; an electric power detection portion for repeatedly detecting an electric power of the desired wave component of the received second CDMA radio wave signal; an averaging portion for averaging the repeatedly detected electric power to obtain an average; a comparing portion for obtaining an error between the average and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value.
According to the present invention, a third communication apparatus is provided, which comprises: a transmitting and receiving portion having an antenna for transmitting a first CDMA radio wave signal including a control signal, receiving a second CDMA radio wave signal, and detecting a desired wave component and interference wave components from the second CDMA radio wave signal; a first electric power detection portion for detecting a first electric power of the desired wave component; a second electric power detection portion for detecting a second electric power of the detected interference wave components; an operation portion for operating a signal to interference power ratio from the detected first and second electric powers; a comparing portion for obtaining an error between the signal to interference power ratio and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value.
According to the present invention, a fourth communication apparatus is provided, which comprises: a transmitting and receiving portion having an antenna for transmitting a first CDMA radio wave signal including a control signal, receiving a second CDMA radio wave signal; an error rate detection portion for detecting an error rate from the received second CDMA radio wave signal; a comparing portion for obtaining an error between the error rate and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value.
According to the present invention, a communication system is provided, which comprises a plurality of mobile stations and a base station. Each of the mobile stations comprises: a receiving and transmitting portion having a first antenna for receiving a first CDMA radio wave signal, detecting a first desired wave component including a control signal, and transmitting a second CDMA radio wave signal; a detection portion for detecting an electric power of a first desired wave component of the received first CDMA radio wave signal; a table portion for storing a relation between the detected electric power and an electric power of the second CDMA radio wave signal to be transmitted, the control signal indicating compensation of the relation; a demodulation and detection portion for demodulating the received first desired wave component and outputting demodulation data and for detecting the control signal from the received first desired wave component; a compensation portion for compensating the relation in accordance with the detected control signal; a determining portion for determined an actual electric power of the second CDMA radio wave signal to be transmitted in accordance with the compensated the relation; and a transmission power control portion for controlling a transmission power of the second CDMA radio wave signal in accordance with the actual electric power.
The base station comprises: a transmitting and receiving portion having a second antenna for transmitting the first CDMA radio wave signal including the control signal, receiving the second CDMA radio wave signal, and detecting a second desired wave component from the second CDMA radio wave signal; an electric power detection portion for repeatedly detecting an electric power of a second desired wave component of the received second CDMA radio wave signal; an averaging portion for averaging the repeatedly detected electric powers to obtain an average; a comparing portion for obtaining an error between the average and a target value and comparing the error with a predetermined value; and a control signal generation portion for generating the control signal when the error exceeds the predetermined value.
In the communication system, each of the mobile stations may further comprise: a sampling and storing portion for sampling and storing the detected electric power; and a compensating range determining portion for determining a portion of a range of the detected electric power in accordance with the stored detected electric power, wherein the compensation portion compensates the relation within the range.
In the communication system, the compensation portion comprises an allowable range data receiving portion for receiving allowable range data and the compensation portion compensates the relation within the allowable range of the electric power of the second CDMA radio wave signal to be transmitted in accordance with the received allowable range data.